Fuel injectors are sometimes used to inject high pressure fuel into cylinders of combustion engines. Specifically, the high pressure fuel is directed into tips of the fuel injectors. Each of these tips includes one or more orifices. The high pressure fuel passes through these orifices into one of the cylinders. To enhance operation of the combustion engine, the orifices are precisely formed to have a particular profile and an opening diameter. Historically, these orifices have been formed through percussion laser drilling. Although effective in some applications, percussion laser drilling may be limited in that it may be incapable of producing a reverse taper in an orifice of a fuel injector tip (i.e., a generally conically-shaped hole originating from a larger internal diameter and terminating at a smaller external diameter of the injector tip).
One attempt to produce a reverse tapered orifice in a fuel injector tip is disclosed in U.S. Pat. No. 6,642,477 (the '477 patent) issued to Patel et al. on Nov. 4, 2003. In particular, the '477 patent describes a machining process whereby the orifice is drilled by a laser beam directed at an external surface of the injector tip. To produce the reverse taper, the external surface is tilted relative to the laser beam and rotated about an axis such that an ablation region, following a full 360° rotation, delimits the reverse tapered orifice. In this manner, each orifice has a larger opening at one side of the fuel injector tip wall than at the other side.
Although the machining process described in the '477 patent may produce an orifice having a reverse taper, it may not help prevent undesirable melting within the ablation region during the drilling. In particular, the described process may not compensate for changes to the ablation region during the drilling. For example, the described process may not compensate for translational movement of the external surface relative to a focal point of the laser beam. Additionally, the described process may not compensate for partially ablated material (i.e., material that has not been fully ejected from the ablation region), which may block the laser beam. The translational movement and the blocking of the laser beam may decrease a machining power of the laser beam, causing melting within the ablation region.
The present disclosure is directed to overcoming one or more of the problems set forth above and/or other problems in the art.